Gear Cog 58 teeth, 1st gear,

"old PX" for Vespa PX125 E/Lusso 1°, Ø 117 mm

The arrangement of gear cogs on the output shaft combined with the smaller cogs of the primary drive assembly form together the final drive ratio of your motors gearbox setup. If this is not, quite literally, geared to the needs of the other components included in the motor, even the strongest cylinder will not help. You can either be constantly revving the life out of your motor or not have enough momentum available to change up to the gears. A cleverly chosen final drive ratio, often achieved by the replacement of just one gear cog, can work wonders to your acceleration and gear changing process.

Gear cogs, as with any other mechanical component, are exposed to wear and tear. Motors with higher mileage or performance show obvious signs of mechanical erosion, especially in the grooves where the gear selector cruciform sits during use. If they are rounded of or otherwise damaged they will need replacement.